1. Field of the Invention
The present invention relates to a method for manufacturing a photoelectric converting device sealed with translucent resin, such as photosensor, solar cell, light-emitting device or the like.
2. Related Background Art
Resin-sealed semiconductor devices, such as solid-state image sensors, have been manufactured in the following manner. As shown in FIGS. 1 and 2, a semiconductor element 32 fixed on a substrate 31 is provided with electrode pads 39. Around said semiconductor element 32 there are provided internal leads 33. Said electrode pads 39 and internal leads 33 are electrically bonded with metal wires 34, and, after the assembly is placed in a sealing mold 41, sealing resin is injected therein.
In such a method, the injection gate for the sealing resin has to be in a broken-lined position 37a or 37b in FIG. 2, in order to eliminate any unfilled portion in the mold 41. There are provided air vents 44 as shown in FIG. 2, in order to remove the air from the cavity.
However, if the resin injecting gate is positioned at 37a or 37b in a photoelectric converting device, such as a CCD, solely in consideration of eliminating the unfilled portion, the fluid translucent resin injected from said gate touches the wires 34 present between said gate and a light-receiving area 36, and the state of flow of the resin is therefore influenced.
Consequently, after the solidification of the resin, there is generated an area 38 with an uneven refractive index, extending even to the light-receiving area of the photoelectric converting device.
FIG. 3 is an enlarged view of an area 38 of uneven refractive index generated in the vicinity of a wire 34. Arrows 40 in FIGS. 2 and 3 indicate the flow of the translucent resin injected from the gate.
Thus the wire 34 constitutes a stagnation point in the flow of the translucent resin, causing a change in the flow thereof. Because of such change in the flow, the area 38 of uneven refractive index extends to the light-receiving area 36 on the solid-state image sensor. As a result, in such a photoelectric converting device, the incident light to be detected in the light-receiving area 36 through the translucent resin is improperly refracted or scattered.
Consequently the light to be received by each pixel in the light-receiving area 36 may be decreased in intensity, or erroneously introduced into other pixels.
In a system of which a function is controlled through the measurement of intensity or distribution of light within a photoelectric converting device such as a solid-state image sensor, such a phenomenon gives rise to an erroneous operation of the system. For example, in case a distance measuring sensor for an automatic focusing single-lens reflex camera is composed of a photoelectric converting device composed of a solid-state image sensor sealed in transparent epoxy resin, such a phenomenon results in an aberration of the focusing operation, so that properly focused photographs cannot be obtained.
As an example, let us consider a case of a photoelectric converting device having a light-receiving area formed as two serial rows on a same chip, each row having 48 pixels of 30 .mu.m.times.150 .mu.m=4500 .mu.m.sup.2 each, and capable of measuring the distribution of light intensity even under a low illumination of EV=1-2. According to the focusing measurement using the solid-state image sensor, the focusing operation is conducted by forming the same image of an object on two photosensor rows through a photographing lens and a glasses lens as a secondary imaging lens or re-imaging lens, which comprises two lens like a glasses, and then moving the photographing lens in a position where the difference between the light intensity distributions detected by said two photosensor rows becomes zero, thus obtaining the focused state (not shown).
Consequently errors in the measurement of the focus state will occur if such a solid-state image sensor contains an area of aforementioned uneven refractive index in the light path in the transparent sealing epoxy resin, leading to the light receiving area.
Such errors in the measurement of the focus state may also appear as a distortion in the photographed image, in case of an area sensor having a two-dimensionally wide light-receiving area as a light-receiving portion.
Further, in case this photoelectric covnerting device is a light-emitting element and used in a semiconductor laser or the like, the rectilinear propagation properties of the light may be damaged because of the area of uneven refractive index.